Relative migratory aptitudes of hydrogen, benzoyl, 4-methoxyphenyl and 4-nitrophenyl groups in some unsaturated carbenes (vinylidenes)

N-Morpholinomethyl-5-lithiotetrazole: A Reagent for the One-Pot Synthesis of 5-(1-Hydroxyalkyl)tetrazoles

An efficient, one-pot method for the preparation of 5-(1-hydroxyalkyl)tetrazoles is reported. N-Morpholinomethyl-5-lithiotetrazole, generated by the deprotonation of 4-(N-tetrazolylmethyl)morpholine with LiHMDS, undergoes addition to ketones and aldehydes (both aromatic and aliphatic) to form 5-(1-hydroxyalkyl)tetrazoles in a high yield, after acidic workup. The reported protocol displays a broad substrate scope and functional group tolerance, avoids the use of cyanide- or azide-based reagents, and provides access to sterically congested and unsaturated tetrazoles, which are difficult to access by other means.

The Fritsch-Buttenberg-Wiechell rearrangement: modern applications for an old reaction

The Fritsch-Buttenberg-Wiechell rearrangement of carbene/carbenoid intermediates has evolved into a valuable synthetic methodology for the preparation of polyyne structures. Various synthetic routes toward the formation of the corresponding precursors, alkynyl-substituted dibromoolefins, have been developed. Additionally, the scope of this methodology is expanded significantly by the development of functional group-tolerant one-pot procedures. The preparation of various polyynes up to the octa- and decaynes is, thus, possible on a scale that enables thorough physico-chemical characterization. Hence, series of polyynes have been investigated by, e.g., UV-vis, IR- and Raman spectroscopy, as well as X-ray crystallography. These investigations give unique insight into the structural characteristics of longer polyynes and hint to the structure of carbyne.